Electromagnetically induced transparency with Rydberg atoms

We present a theory of electromagnetically induced transparency in a cold ensemble of strongly interacting Rydberg atoms. Long-range interactions between the atoms constrain the medium to behave as a collection of superatoms, each comprising a blockade volume that can accommodate at most one Rydberg excitation. The propagation of a probe field is affected by its two-photon correlations within the blockade distance, which are strongly damped due to low saturation threshold of the superatoms. Our model is computationally very efficient and is in quantitative agreement with the results of the recent experiment of Pritchard et al. [Phys. Rev. Lett. 105, 193603 (2010)].     

调制激光场中Rydberg原子的电磁感应透明

本文主要研究了调制探测激光场中铯Rydberg 原子阶梯型三能级系统的电磁感应透明(EIT) 效应. 铯原子基态6S_1/2, 第一激发态6P_3/2 和Rydberg 态形成阶梯型三能级系统, 探测光作用于6S_1/2 (F = 4)→6P_3/2(F' = 5) 的跃迁, 耦合光在Rydberg 跃迁线6P_3/2→49S_1/2 附近扫描, 形成Rydberg 原子EIT. 当对探测光频率施加一个几kHz 的调制时, 调制解调后的EIT 信号分裂为两个峰, 双峰间距与调制频率无关,而与调制幅度导致的失谐量大小(频率调制幅度) 成正比, 双峰间隔的一半等于探测光频率调制幅度的λ_p/λ_c = 1.67 倍. 实验结果与理论计算相一致. 本文的研究结果可应用于激光线型和频率抖动的实时监测.     

Field-driven super/subradiant lasing without inversion in three-level ladder scheme

A model of a superradiant laser comprising of N three-level systems driven by two pumping lasers is considered in semiclassical approximation. Steady-state equations for density matrix elements are solved both analytically and numerically. Various properties of generated light are investigated. It is found that such a laser can exhibit both superradiance, when the intensity scales as N(2), and subradiance when the intensity does not depend on N. The phase of the laser field is locked to the relative phase of the pumping lasers.     

Time-dependent dressed-states analysis of lasing without population inversion in a three-level ladder scheme

A dressed-state study of lasing without population inversion from a three-level atom interacting with a bichromatic laser field in the ladder configuration is being formulated. The system is allowed to be dressed by both laser-field photons (double dressing). The temporal behavior of the system under consideration is being explored numerically. Although the use of dressed-basis density matrix equations introduces major complexity into the equations, this procedure has crucial importance to the understanding of the atomic spectrum and the underlying physics of the processes involved. The system is found to possess a gain without population inversion, as well as a regular gain with inversion for various transitions, both in the transient and steady-state regimes. Enhancement of the refractive index accompanied by vanishingly small absorption was also found. The frequency response of various transitions is explored via numerical Fourier analysis. Some transitions are found to exhibit a dispersion-like line shape, clear evidence of a quantum-coherent interference effect. The spectrum consists of two distinct quintets centered about the coupling and probe-laser frequencies. The spectral features consisting of each quintet are located symmetrically (at resonance conditions only) around the line center at positions shifted from the center by the generalized Rabi and double Rabi frequencies.     

Nonlinear theory of lasing with or without inversion in a simple three-level atomic system

We investigate, using a nonlinear theory of laser physics, for a simple three-level atomic system the steady-state intensity behavior due to the effects of quantum coherence and decoherence. We find that a change from a noninversion laser to an inversion laser action can occur as the Rabi frequency of the driving field increases. The steady-state intensity of the laser field can arrive at a maximal value for a certain Rabi frequency of the driving field. We also find that the linear gain and the laser intensity tend to decrease for the linewidth of the driving field.     

Electromagnetically induced transparency in a non-uniform plasma

Electromagnetically induced transparency in a non-uniform plasma is investigated. We discuss the possible frequency ranges in which a weak beam below cutoff can propagate transparently in this plasma with the presence of a strong high frequency field. We also analyze the effect of driving intensity on the frequency range of the probe. Received 3 March 2000 and Received in final form 21 April 2000     

Electromagnetically induced transparency in a molecular gas

The dynamic Stark effect on the as Q(5,4) transition of the 0 → 1 vibrational band of the ν₂ mode of ammonia ¹⁵NH₃ was studied by the method of copropagating waves of radiation of two ¹³CO₂ lasers operating at the R(18)_I line. For waves with mutually orthogonal polarizations, which propagated in a waveguide cell, the intensity of the saturating radiation reached 225 W/cm², and the absorption line of the probing radiation had the form of a two-hump curve with a splitting that was consistent with the Rabi frequency for the ammonia transition being investigated. At the maximum intensity of the saturating radiation, complete transparency was observed at the center of the absorption line of ¹⁵NH₃. When identically polarized saturating and probing waves propagating in a cell at a small angle with respect to each other were used, the splitting was more weakly manifested. The effect of a spatial inhomogeneity of the optical fields on the shape of the line of saturated absorption is discussed.     

Electromagnetically induced transparency in the medium of four-level atoms with upper level doublet

Light absorption and slowing down when traveling in a medium of four-level atoms with a doublet of close-lying upper levels is studied in conditions of electromagnetically induced transparency (EIT). It is shown that the presence of the second upper level leads to an increase in the absorption of the probe pulse. However, a control-pulse-detuning range exists between the doublet levels where light decelerates considerably more than in the case of ideal EIT.     

铷原子耦合光频率近共振时的电磁感应透明

研究了Λ型能级系统中, ⁸⁵Rb原子在耦合光频率失谐较小时的电磁感应透明(EIT)现象. 实验中, 随着耦合光频率失谐量的增加, 电磁感应透明窗口的绝对强度有所减弱, 但是其相对深度却有所增加, 透明窗口相对深度最大的位置不在耦合光频率共振处, 而是在耦合光频率失谐约180 MHz的位置. 用三能级和四能级系统的理论分别对实验结果进行对比分析, 发现用四能级系统的理论进行拟合的结果与实验符合得比较好. 对此, 我们提出当耦合光频率失谐较小时, EIT信号是两个激发态共同作用的结果, 并用四能级系统的理论分析了两个激发态之间的能级间隔对透明窗口相对深度最大值位置的影响.     

Electromagnetically induced transparency in a three-mode optomechanical system

We study a three-mode double-cavity optomechanical system in which an oscillating membrane of perfect reflection is inserted between two fixed mirrors of partial transmission. We find that electromagnetically induced transparency （EIT） can be realized and controlled in this optomechanical system by adjusting the relative intensity and the relative phase between left-hand and right-hand input （probe and coupling） fields. In particular, one perfect EIT window is seen to occur when the two probe fields are exactly out of phase and the EIT window＇s width is very sensitive to the relative intensity of two coupling fields. Our numerical findings may be extended to achieve optomechanical storage and switching schemes applicable in quantum information processing.     

压缩真空中的电磁诱导透明

从主方程出发,通过解析求解密度矩阵非对角元,研究了压缩真空中Λ型三能级原子的电磁诱导透明现象(EIT).研究结果表明:EIT显著地依赖于相干光场的相位、压缩真空的压缩强度和压缩相位.Λ型三能级原子不但有电磁诱导透明和慢光速现象,而且还会表现出对探测光的增益、快光速和反向光速效应;且Λ型三能级原子对探测光场的吸收和增益与探测光强度有关,这与普通真空中不同. 关键词： 压缩真空 电磁诱导透明 增益     

Electromagnetically induced acoustic transparency and absorption

The possibility of controlling the passage (from transmission to absorption) of a hypersound through a low-temperature paramagnet using the resonance electromagnetic pumping of lower frequency is substantiated. The effect has a quantum nature and is analogous to (though somewhat different from) the optical phenomenon of electromagnetically induced transparency.     

Electromagnetically induced transparency in five-level cascade scheme of Rb atoms: An analytical approach

Electromagnetically induced transparency (EIT) in the five-level cascade scheme of ⁸⁵Rb atoms is investigated by analytical method. In the weak field limit of the probe light, the linear susceptibility, absorption, and dispersion coefficients have been derived in analytical forms. Unusual EIT signatures of the system are studied in details.     

Effect of vacuum-induced coherence on lasing without inversion in an equispaced three-level ladder system

The effects of vacuum-induced coherence (VIC) on the properties of the absorption and gain of the probe field in an equispaced three-level ladder atomic system are investigated. It is found that lasing without inversion (LWI) is remarkably enhanced due to the effect of VIC in the case of the small incoherent pump rate.     

Electromagnetically induced transparency in degenerate two-level systems

The evolution of an electromagnetic wave with slowly varying polarization, which interacts resonantly with the medium formed by degenerate two-level atoms, is studied using the wave function approach under the conditions of electromagnetically induced transparency. It is shown that the amplitude of the wave field propagates at the velocity of light in such a medium. The equation obtained for the polarization parameter has a solution in the form of a simple wave. The breaking length is determined. It is shown that the velocity of propagation of polarization waves may be much smaller than the velocity of light. The proposed approach is common for two-level systems with an arbitrary degeneracy. The case of a system with Zeeman degeneracy is analyzed in detail. The dependence of the velocity of propagation of the polarization structure on the amplitude and polarization is determined for an arbitrary level degeneracy. The evolution of the polarization structure in such a medium is discussed.     

固体介质中的电磁感应透明效应及其应用

电磁感应透明技术不仅能够改变物质对光场的响应，而且能够调控光场本身的性质．文章介绍了电磁感应透明效应的基本原理，电磁感应透明现象在各种固体介质中的实现，比较了这些固体介质的特性，并讨论了由电磁感应透明现象所产生的各种效应及其应用．     

Electromagnetically induced transparency in a Zeeman-sublevels Λ-system of cold ~(87)Rb atoms in free space

We report the experimental investigation of electromagnetically induced transparency(EIT) in a Zeeman-sublevelsΛ-type system of cold ~(87)Rb atoms in free space. We use the Zeeman substates of the hyperfine energy states 5~2S_(1/2), F = 2 and 5~2P_(3/2), F = 2 of ~(87)Rb D_2 line to form a Λ-type EIT scheme. The EIT signal is obtained by scanning the probe light over 1 MHz in 4 ms with an 80 MHz arbitrary waveform generator. More than 97% transparency and 100 k Hz EIT window are observed. This EIT scheme is suited for an application of pulsed coherent storage atom clock(Yan B, et al. 2009 Phys.Rev. A 79 063820).